Sofikitis Dimitris, Rubio-Lago Luis, Bougas Lykourgos, Alexander Andrew J, Rakitzis T Peter
Department of Physics, University of Crete, 71003 Heraklion-Crete, Greece.
J Chem Phys. 2008 Oct 14;129(14):144302. doi: 10.1063/1.2989803.
Thermal HCl and HBr molecules were photodissociated using circularly polarized 193 nm light, and the speed-dependent spin polarization of the H-atom photofragments was measured using polarized fluorescence at 121.6 nm. Both polarization components, described by the a(0)(1)(perpendicular) and Re[a(1)(1)(parallel, perpendicular)] parameters which arise from incoherent and coherent dissociation mechanisms, are measured. The values of the a(0)(1)(perpendicular) parameter, for both HCl and HBr photodissociation, are within experimental error of the predictions of both ab initio calculations and of previous measurements of the polarization of the halide cofragments. The experimental and ab initio theoretical values of the Re[a(1)(1)(parallel, perpendicular)] parameter show some disagreement, suggesting that further theoretical investigations are required. Overall, good agreement occurs despite the fact that the current experiments photodissociate molecules at 295 K, whereas previous measurements were conducted at rotational temperatures of about 15 K.
利用圆偏振193纳米光使热HCl和HBr分子发生光解离，并使用121.6纳米处的偏振荧光测量H原子光碎片的速度依赖自旋极化。测量了由非相干和解离机制产生的a(0)(1)(垂直)和Re[a(1)(1)(平行,垂直)]参数所描述的两个极化分量。对于HCl和HBr光解离，a(0)(1)(垂直)参数的值均在从头算计算以及卤化物共碎片极化先前测量的预测实验误差范围内。Re[a(1)(1)(平行,垂直)]参数的实验值和从头算理论值存在一些分歧，这表明需要进一步进行理论研究。总体而言，尽管当前实验是在295 K下使分子发生光解离，而先前测量是在约15 K的转动温度下进行的，但仍达成了良好的一致性。
